Exhaust hood



April 4, 1944.

s. E. wooDBuRY EXHAUST HOOD Filed May 5, 1943 2 Sheets-Sheet 1 4INVENTOR. M... (Mm-3' April 4, 1944.

- S. E. WQODBURY -EXHAUST HOOD Filed May 5, 1943 2 sheets-sheet 2INVENTOR. r BY 'drm E@ Patented Apr. 4, 1944 UNI-TED STATES PATENTOFFICE EXHAUST HOODA Stephen E. Woodbury, Beverly, Mass., assigner toReid Brothers Company, Inc., Beverly,'Mass.,a corporation ofMassachusetts f Application May 5, 1943, seria1.No. 485,748

r claims. (or tl-evsy This invention relates to an exhaust hood.

The invention has for an object to provide a novel and improved exhausthood particularly adapted for use in a vacuum operated, exhaust systemwith a grinding wheel orl other rotating dust creatingmember forenabling the dust laden air created during the rotation of the Wheel incontact with the work to be removed,v and whose construction is such asto contribute greatly to increased efficiency in dust removal..

With this general object in review, and such others as may hereinafterappear, the invention consists in thel exhaust hood, in the. vacuumoperated exhaust system,l and in the. various structures, arrangementsand combinations of parts hereinafter described and particularly definedin the claims at the end of this specification.

In the drawings illustrating the preferred embodiment of the inventionas embodied in avacuum operated dust removal system for a grinding'wheeL Fig. 1 is a front elevation of an exhaust hood embodying thepresent invention shown with the hinged front section removed; Fig. 2 isa plan View of the present exhaust hood; Figs. 3 and 4 are crosssectional views taken on the lines 3-3 and 4 4 respectively of Fig. l;Fig. 5 is an end view in vertical cross section taken n the line 5-5 ofFig. l, and Fig. 6 is a plan view in cross section taken on the line6--6 of Fig. 1.

In general, the. present invention contemplates an improved constructionof. exhaust hood particularly adapted for use with a grinding wheel forremoving-the dust, grit and metal particles created during the grindingoperation, and the present invention seeks particularly to counteractthe eiTect of the centrifugal force of the rotating wheel which normallytends to displace the air outwardly from the hood to thereby greatlyincrease thev efliciency of the dust removal characteristics of theexhausting system.

In observing the behavior of the air adjacent a prior hooded grindingwheel in the operation of a vacuum dust removal system, it appears thatthe wheel entrains considerable air upon its rough sides, causing` afan-like eiTect, setting up air currents resulting in a strong outwardflow of air from the hood opening. Thus it will be seen that the vacuumprovided in the hood by the exhaust system, to which the hood isconnected, is substantially neutralized or, at least, greatly reduced ineiectiveness so that but a small part of the dust laden air enters thehood. In practice, the particles of grit and metal leave the wheel atrelatively high velocity,y and this movement together with the outward.flow of theair as' above. .described causes the particles tocontinue'outwardly beyondk the hood, onlythose relatively heavyparticles which are bodily thrust into thehood finding their way intothe` exhaust system'. Thus it will be'seen that such prior exhaust:hoods are. ineffective to remove, the dust laden air efficiently.

In, accordance with. the present invention, provisionis made forreducing to aminimum the displacement of air caused by the rotationA ofthe wheel,. preferably' by applying a. vacuum to both sides of the Wheelwhereby to set up an opposing force drawingv the air inwardly towardsthe center .,of, the Awheel and counteracting the outward how` of.y aircaused bythe centrifugal force. As aresuitoi thisneutralizing.action,..the main hood opening` isY enabled to operate withincreased e-; ciency, so as. .to remove practically all the dust laden.air. adjacent: the work, being ground. It was. alsofound, inpractice,that asa result of the counteracting current of air being drawn inwardlyfrom the sides of the wheel towards the center thereof., af relativelyWeak vacuum at the main hocdeopening permits the atmospheric pressure todrive the `dust laden air` into the. hood. In other words, the velocity.of the particles leaving; thewheelis greatly reduced by this expedientsoi that a relatively low degree. of vacuum is sufficient, to: draw theparticles into the exhaust system. Referring now to the drawings whichillustrate the preferred embodiment of the invention,y the presentexhaust hood, represented generally by thenumeral lla comprises anarcuate casing l2 formed about the upper portion of a grinding wheeliii, shown in dotted lines, the bottom of the vcasing being providedwith an opening I6 adjacent the work l 8 which is mounted on andmovable: with the reciprocable table 20 of ar grinding machine, Thearcuate casing is connected by a, laterally extending and tapering duct22 to a cylindrical duct 2li which latter may and preferably will beconnected to piping, notl shown, forming part of `anl air exhaustingsystem. A vacuumis produced in the casing for drawing the dust laden airadjacent the work into the opening i6. 'In the. illustrated embodimentof theinvention, the tapering duct 22 extends from the left of thecasing I2, as viewed in Fig. l, in apcsition to receive the grit andmetal particles-being projected from the clockwise rotating;grindingwheel I4 in contact with the Work. As-shown in Fig. 5, thecasing is also provided with a. rearwardly extended arcuate portion 26having-aa flange; 2-8-.bolted` .to avertically adjpst.

able spindle bearing 30 of the grinding machine.

As herein illustrated, the arcuate casing, indicated generally at I2, isprovided with an inner chamber 32 formed by an inner arcuate wall 34 andside walls 36, 38 having the opening I6 at the bottom and communicatingdirectly with the tapering duct 22. The arcuate casing l2 is alsoprovided with an outer chamber 40 formed about the walls or the innerchamber by an arcuate wall 42 and side walls M, 46. The outer chamber locommunicates with the inner chamber 32 through openings Q8, 50 formed inthe side Walls 3S, 38 respectively, adjacent the central portion of thewheel ils', and is provided with a separate air withdrawal duct 52opening into the rear of the casing i2 and leading to lthe duct 24connected to the exhaust system, as clearly shown in Fig. 6. The frontportion 54 of the casing I2 is preferably hinged as at 56, see Fig. 5,in order to permit such portion to be rocked up out ci the way forconvenience in assembling or replacing a grinding wheel upon the spindle3l. As herein shown, the inner and .outer side walls 36, "i4respectively, form part of the hinged cover portion 5d and when thelatter is closed into assembled relation with the main or body portionof the casing, a continuous duct or chamber 4l] is for-med around thetop and sides of the wheel, the bottom portion being closed by integralbottom walls 58, and 60.

In the operation of the device as thus constructed and as abovedescribed, it will be seen that any air pressure built up within thehooded portion of the exhaust hood by the rotation of the wheel or anyair currents created thereby tending to force the air outwardly from thehood are eiiectively counteracted and substantially neutralized by thenovel application of the vacuum to the Wheel. It will be observed that avacuum is applied toboth sides of the wheel, and as indicated by thearrows in Fig. 5, the air currents set up in the open chamber 32 by therotation oi the wheel are diverted from their travel in an outwarddirection and caused to turn about and enter either side of the chamber40 through the openings 48 and 55 adjacent the center of the wheel, or,more correctly, the air pressure is substantially neutralized to renderinelective the outward flow of air. As shown in Fig. 5, the air passingthrough the opening 50 in the side wall 38 passes almost directly itnothe duct 52, and the air passing through the opening A8 in the oppositewall 36 is directed outwardly and around the inner wall 3i into the duct52, which, as above stated, communicates with the duct 24 andtheexhausting system.

From the description thus far it will be seen that with the air movementwithin the hood thus substantially neutralized, the suction opening I6in the bottom of the hood is enabled to operate with maximuml efficiencysince the vacuum applied at this opening is not required to overcome theoutward iow of air as was formerly necessary and thus is enabled to morereadily pick up the dust, grit and metal particles created during thegrinding operation and to carry them away through the duct 22 and intothe exhaust system, In practice it was found that a relatively slightreduction in pressure at the opening i6 is eiective to cause the dustladen air to enterthe hood. Thus, the amount of vacuum required toneutralize or substantially nullify the outward iiow of air and to alsodraw the dust laden air into the hood, need not exceed the amount ofvacuum normally applied at the opening I6 alone in prior exhaust hoods,the present invention effecting a more efiicient distribution thereof. ll

While the preferred embodiment of the present invention has been hereinillustrated and described, it will be understood that the invention maybe embodied in other forms within the scope of the folowing claims. Y i

Having thus described the invention, what is claimed is:

1. In an exhaust system for a grinding wheel or the like, a hoodenclosing the major portion of the wheel and having an opening in thebottom thereof, a main exhaust duct communicating with the hood forcarrying away the dust, grit and metal particles created during thegrinding operation, and means for counteracting the effect of airmovement created by the rotation of the wheel comprising an auxiliaryduct connected to a source of suction and communicating with openingsformed in either side oi said hood adjacent the center of the wheelwhereby to enable said main exhausting duct to operate with increasedeliiciency. v

2. In an exhaust system for a grinding Wheel or the like, a hoodenclosing the major portion of the wheel and having an opening in thebottom thereof, a main exhaust duct communicating with the hoodforcarrying away the dust, grit and metal particles created during thegrinding operation, and means for reducing to a minimum the outward lowof air as eiected by the rotation of the wheel comprising an auxiliaryduct connected to a source of suction and communicating with openingsformed in either side of said -hood adjacent the center of the wheelwhereby to eiect a reduction in the velocity of the particles detachedfrom the grinding wheel during the grinding operation and to thus enablesaid main exhausting duct to operate with increased eiilciency.

3. In an exhaust system for a grinding wheel or the like, a hoodenclosing the major portion of the wheel and having an opening in thebottom thereof, a main exhaust duct communicating with the hood forcarrying away the dust, grit and metal particles created during thegrinding operation, and means for substantially equalizing the pressurebuilt up within said hood by the rotation of the wheel comprising anauxiliary duct connected to a source of suction and communicating withopenings formed in either side of said hood adjacent the center of thewheel whereby to eiect a reduction in the velocity of Ythe particlesdetached from and created by the wheel during the grinding operationthus permitting said main exhaust duct to operate with increasedefficiency.

4. In an exhausting device for a grinding wheel o1' the like, an innerhood enclosing the major portion of the wheel and forming a chamberhaving an opening in the bottom thereof, a main exhausting ductcommunicating with said chamber and disposed to receive the dust, gritand metal particles created during the grinding operation, and means forreducing to a minimum the outward flow of air as eiected by the rotationof the wheel including an outer hood spaced from said inner hood andforming therewith a second chamber provided with openings directedtoward each side of the wheel adjacent the center thereof, and anauxiliary exhausting duct comrnmu'nicating with said second chamberwhereby to counteract said outward flow of air to permit said mainexhausting duct to operate with increased eiciency. i f

5. In an exhausting system for a grinding wheel or the like, an innerhood extending about the major portion of the circumference of the wheeland around each side thereof forming a chamber having an opening in thebottom thereof, a main exhausting duct communicating with siad chamberand disposed to receive the dust, grit and metal particles createdduring the grinding operation, an outer hood spaced from said inner hoodand forming therewith a second chamber comprising a continuous ductbetween said inner and outer hoods provided with openings directedtoward each side of the wheel adjacent the center thereof, and anauxiliary eX- hausting duct communicating with said second chamberwhereby to counteract the outward iiow of air as effected by therotation of the wheel and thus permit said main exhausting duct to ooperate with increased efficiency.

6. In an exhaust system for a grinding wheel or the like, a hoodenclosing the major portion of the wheel and having an opening in thebottom thereof, a main exhaust duct communicating with the hood forcarrying away the dust, grit and metal particles created during thegrinding operation, and means for counteracting the effect of airmovement created by the rotation of the wheel comprising an auxiliaryduct connected to a source 0f suction and communicating with openingsformed in either side of said hood 30 adjacent the center of the wheelwhereby to enable said main exhausting duct to operate with increasedeiiciency, one side of said hood being hinged with relation to theremainder of the hood whereby to permit replacement of a wheel withoutremoving the hood,

7. In an exhausting system for a grinding wheel or the like, an innerhood extending about the major portion of the circumference of the wheeland around each side thereof forming a chamber having an opening in thebottom thereof, a main exhausting duct communicating with said chamberand disposed to receive the dust, grit and metal particles createdduring the grinding operation, anv outer hood spaced from said innerhood and forming therewith a second chamber comprising a continuous ductbetween said inner and outer hoods provided with openings directedtoward each side of the wheel adjacent the center thereof, and anauxiliary exhausting duct communicating with said second chamber wherebyto counteract the outward flow of air as eifected by the rotation of thewheel and thus permit said main exhaustingduct to operate with increasedeiiiciency, one side of the combined hood being hinged and provided withduct forming portions arranged to abut with similar portions of theremainder of the hood to form said continuous duct.

STEPHEN E. WOODBURY.

